Typically, mail is received in a distribution center or warehouse from two sources. One source or type is local mail which is to be delivered within the local area. This is commonly known as turnaround mail. Local mail may also be sorted for delivery to other distribution centers. Another source or type of mail is out-of-area mail received from other distribution centers. Mail which is to be delivered locally must, ultimately, be sorted to delivery point sequence, also known as “carrier walk sequence,” i.e., the mail is sorted and arranged such that the first address stop is followed by the second address stop, which is followed by the third address stop, and so on. A Dual Bar Code Sequenced (DBCS) machine is capable of achieving delivery point sequence for letter mail. However, it requires two or more passes of the mail through the same sequence.
A process exists today to delivery point sequence letter sized mail, which sorts the mail into a specific mail carrier's route sequence. The approach commonly used to sequence the letter mail requires that the mail be processed through a Letter Sorting Machine (LSM) twice. Each of these two sort processes is referred to as a pass. The first pass inducts mail, which arrives in somewhat random order, into an LSM, which arranges it into groupings of addresses. The number of discreet addresses (sequences) in each grouping depends on how many output bins of the LSM are utilized in the sorting process.
The device used to provide places to hold the mail in order is a sorting matrix, such as a grouping of slots, with each slot representing an address in the carrier's route. This sorting matrix can be as large or as small as necessary or desired. For example, a larger matrix (or number of slots) allows for a larger carrier route or more individual smaller carrier routes to be processed at one time. If an LSM contains output bins equal to the number of stops on the carrier's route, then mail for each address would be sorted to one bin. However, to be able to process more carrier routes at one time, a theoretical grouping of sorting slots is created using a specific number of LSM output bins. The number of slots is typically equal to the number of bins squared. For example, if an LSM is equipped with 10 output bins, a matrix of 100 slots can be created.
Therefore, mail for the first carrier route address or sequence may be sorted to the first assigned bin, the second address to the second bin, the third sequence to the third bin and so on to the tenth bin. The eleventh sequence may then be sorted to the first bin, the twelfth to the second bin, and so on, up to the twentieth sequence being sorted to the tenth bin. This same sorting process is repeated so that the first, eleventh, twenty first, thirty first and so on, up to and including the ninety-first sequence, are sorted into the first bin, while the second, twelfth, twenty-second, thirty-second, etc. sequences are sorted into the second bin and so on for all ten output bins.
Having completed the first sorting pass, mail is usually manually removed from the LSM and loaded onto manual carts and/or temporarily stored on shelves in racks in preparation for the second pass. The trays are then unloaded from the manual carts and the sorted articles in the trays are reprocessed during a second pass. An alternative to manual handling of the trays of mail between sort passes is disclosed in U.S. Pat. No. 5,385,243, which utilizes a storage and retrieval machine to stage the letter trays for the second pass.
For the second pass, it is absolutely essential that proper order of trays be maintained. First pass mail trays from bin number one of the first pass must be inducted into the LSM first, followed by the trays of bin number two, three and so on up to bin number ten. The current process requires machine operators to properly maintain this sequence. When inducted for the second pass, the sequences are sorted with address or sequence 1 being sorted to bin 1, sequence 11 to bin 2, sequence 21 to bin 3, and so on up to sequence 91 to bin 10. Trays of mail for the second bin (containing sequences 2, 12, 22, 32, 42, 52, and so on up to 92) are inducted and sorted such that address or sequence 2 is sorted to bin 1, sequence 12 to bin 2, sequence 22 to bin 3, etc. When the trays of mail sorted at all ten bins during the first sort pass are inducted and sorted during a second sort pass, bin 1 will contain sequences 1 through 10, bin 2 will contain sequences 11 through 20, and so on.
Accordingly, when the second sort pass is completed and the mail is removed from the LSM, it is sorted in carrier route sequence, i.e., first address stop followed by second address stop followed by third address stop, etc. The delivery point sequence sorting matrix described above is recognized as the process currently utilized for letter mail, and can be adapted to flat mail sequencing. However, as discussed above, this process requires manual handling of the trays between sort passes to ensure that the trays are in the proper order or sequence for the second sort pass.
Flat mail is mail which ranges in length from approximately 5 inches to approximately 15 inches, height from approximately 6 inches to approximately 12 inches, thickness from approximately 0.009 inches to approximately 0.75 inches, and weight from approximately 0.01 pound to approximately 1.0 pound. It may include paper envelopes, plastic wrappers, bound catalogs, banded newspapers, open mail pieces without wrappers, and the like. Such flat mail has traditionally been sorted to the distribution center level automatically, such as via a model AFSM 100 flat sorting system manufactured by Mannesmann Dematic Postal Automation and marketed in the United States by Mannesmann Dematic Rapistan Corp. The sortation from distribution center to carrier walk sequence has traditionally been performed manually utilizing pigeon-hole bins. Such manual sorting of flat mail to the delivery point sequence may take several hours, up to half of the time available for a carrier to deliver his/her route.
It would be desirable to provide a carrier walk sequence for mail, especially for flat mail. It would be most desirable if the carrier walk sequence depth of sort is accomplished automatically. It would also be desirable if the carrier walk sequence of flat mail is accomplished irrespective of the source or type of the mail. In particular, it would be desirable to be able to sort turnaround mail to carrier walk sequence.